Thank you, I’ll try and keep it short. I replaced a Mallory distributor with a Progression ignition unit which requires 12v all the time. I bypassed the ballast and all that and it ran good. A bit later I began to have a hard starting problem hot or cold and found low voltage at the coil. In trying to isolate the problem I found it would start if I disconnected the green wire at the alternator which seemed to allow batt volts to the coil at all times. So yesterday, I removed the ground to the starter relay to eliminate the drain of the starter plus I’m not cranking away at a cold engine. Leaving everything else connected I check the voltage at the coil with the key switch at the run position and I get batt volts. If I turn the key to the start position I get like 7volts at the coil. If I disconnect the alternator field wire I now get battery volts at the start position. I don’t know how the alternator could be at fault but disconnecting it makes a difference in the readings.
Your 1.7 ohm reading will be OK. From EITHER slip ring to the rotor shaft should be infinity (no ohms) indicating no grounds. The voltage regulator varies the rotating field windings VOLTAGE and is controlled by the VOLTAGE REGULATOR. It is likely that the voltage regulator is faulty. If its the OEM mechanical voltage regulator, possibly the internal fuse has failed. If its the electronic voltage regulator replacement, the internal transistor, which regulates the 0-7 volts applied to the rotor. IT IS UNLIKELY THAT THE STATOR WINDINGS AND / OR DIODES ARE BAD. The MOPAR charging circuit is simple......just my opinion of course...
Thanks, it’s the newer electronic regulator, I had another I swapped in and it did the same thing, nothing seemed burned on the inside of either of them.
The internal switching transistor, in the electronic voltage regulator, usually fails open.....it does not burn up...but results is zero output to the alternator's rotating field.....and no output current.
That works, it’s what led me to look for bad connections. I took care of what I found at the time and it tested ok but I must have missed something because there’s still a voltage drop coming out of the bulkhead.
Thanks, my regulator is putting out 10v to the rotor, you had mentioned 0-7, I don’t know if that’s a problem or not.
The voltage impressed on the alternator's rotating field can vary from almost 0 volts to 12 volts depending on the battery's state of charge. I mentioned 7 volts as a nominal value or average. Its possible that a poor condition exists at the bulk head and or ignition switch connections. Just an additional thought......
So the jumper worked. Check all connections, bulkhead, ammeter, ignition switch,. What year car?
Ok, that makes sense, my battery isn’t exactly topped off so it sounds like I’m ok there. It’s a ‘69 charger and putting it together I replaced the engine harness and did the MAD electrical amp gauge bypass, and other then the usual issues with the bulkhead, the rest of it was ok. The keys switch was replaced this last summer while chasing this down, mine wasn’t all that bad, but it wasn’t the greatest. It helped a little bit maybe. Just now I checked the resistance from the starter relay through the bulkhead to the coil and had .5 ohms. From the key switch plug to the coil .3 ohms. Start bypass was about the same.
Forget the OHM's. You need to test the circuit under load. It should only take 20 to 30 minutes to check it. Your problem is a constant issue which makes it easier to diagnose.
